Over the years, various experimental methods have been applied in an effort to understand the
blood flow behavior in microcirculation. Most of our current knowledge in microcirculation is based on
macroscopic flow phenomena such as Fahraeus effect and Fahraeus-Linqvist effect. The development of
optical experimental techniques has contributed to obtain possible explanations on the way the blood flows
through microvessels. Although the past results have been encouraging, detailed studies on blood flow
behavior at a microscopic level have been limited by several factors such as poor spatial resolution,
difficulty to obtain accurate measurements at such small scales, optical errors arisen from walls of the
microvessels, high concentration of blood cells, and difficulty in visualization of results due to insufficient
computing power and absence of reliable image analysis techniques. However, in recent years, due to
advances in computers, optics, and digital image processing techniques, it has become possible to combine
a conventional particle image velocimetry (PIV) system with an inverted microscope and consequently
improve both spatial and temporal resolution. The present review outlines the most relevant studies on the
flow properties of blood at a microscale level by using past video-based methods and current micro-PIV
and confocal micro-PIV techniques. Additionally the most recent computational fluid dynamics studies on
microscale hemodynamics are also reviewed.